The present invention relates to a densitometer for an electrophoresis apparatus which permits an examination of a blood serum specimen by electrophoretic process.
An electrophoresis apparatus is employed for the determination of protein contained in a blood serum as in hospitals. The general arrangement of the electrophoresis apparatus, referring to FIG. 1, will be explained as follows. A carrier 1 for a blood serum which may be formed of cellulose acetate film and wound into a roll is drawn out by a pair of rollers 2 and is cut to a given length by a cutter 3 which comprises a stationary and a rotating blade. The carrier 1 thus cut off is fed to a buffer solution vessel 4 to be immersed in a buffer solution and then is fed to a blood serum applicator 5 which applies a blood serum, by a conveyor 5a. The blood serum applicator 5 is provided with an application station 5b where a plurality of application members are arranged in rectilinear form along the direction of movement of the carrier 1. A blood serum, a specimen to be examined, is applied onto the carrier 1 at the application station 5b. The blood serum is contained in a serum dish assembly 5c which is disposed at a position directed to the application station 5b. The blood serum applicator 5 further includes a rinsing vessel 5d and a drip device 5e. After applied with a blood serum, the carrier 1 is fed to an electrophoresis station 6 which includes a film conveyor 6a and an electrophoresis compartment 6b. At the electrophoresis station 6, a d.c. voltage is applied to both ends of the carrier 1 in the direction y (perpendicular to paper) which is also perpendicular to the direction x along which the carrier 1 is coveyed. As a result of the energization of carrier 1, protein components such as albumin, .alpha., .beta., .gamma.-globulin are fractionated in the direction y in accordance with their respective mobilities and the resulted fractionated patterns are formed as shown in FIG. 2, for example. The carrier 1 carrying the fractionated patterns thereon is supplied to a dyeing unit 7a, a decolorizing unit 7b and a drying unit 7c. The carrier 1 is finally fed to a densitometer 10.
The densitometer 10 comprises a clearing liquid vessel 12 which contains a clearing liquid 11 for rendering the carrier 1 for a blood serum which is formed of cellulose acetate film clear, a plurality of pairs of rollers 13a.sub.1, 13b.sub.1 to 13a.sub.4, 13b.sub.4 (four pairs shown in FIG. 1) as a carrier supporting member which is disposed within the clearing liquid vessel 12, a photometry unit which comprises a light projector 14 and a light receiver 15 between which the bottom of the clearing liquid vessel 12 is disposed and a cover 16 for preventing outside light from entering. The projector 14 comprises a lamp 17, a condenser lens 18 and a perforated member 19. The receiver 15 comprises a photoelectric transducer 20. A transparent plate 21 such as a glass plate is provided in the middle of the bottom of clearing liquid vessel 12. The light incident surface of the receiver 15 is immersed in the clearing liquid vessel 11 so as not to be subject to a disturbance such as turbulence of the surface of the clearing liquid 11.
When the carrier 1 carrying a blood serum is fed into the densitometer 10, the film is immersed in the clearing liquid 11 to render it clear and only fractionated patterns of a blood serum on the carrier 1 clearly appear. The carrier 1 is then fed between the projector 14 and the receiver 15 where the receiver 15 detects light which is emitted from the projector 14 and passes through the carrier film. As such, the fractionated patterns are measured as a variation in density in accordance with a shade of color for impression of electrophoresis on the carrier 1. While in the density measurement with the densitometer 10, the carrier 1 is positioned in the direction x shown in FIG. 2 by means of rollers 13a.sub.1, 13b.sub.1 through 13a.sub.4, 13b.sub.4 in such a manner that the center of fractionated patterns of each blood serum coincides with the center of a photometric spot and then the measurement is effected by scanning both the projector 14 and the receiver 15 in the direction y shown in FIG. 2. During the scanning in the direction y, the receiver 15 produces an output in accordance with a distribution of variation in density and thus a quantitative and qualitative analysis of protein in a blood serum is effected with the distribution of variation in density. The scanning in the direction y is successively conducted whenever positioning of each carrier carrying a specimen to be examined at a pitch for each blood serum in the direction x is terminated and the above-mentioned operation is successively repeated to measure density of fractionated patterns for all blood serums on the carriers 1 which have been cut to a given length.
The conventional densitometer 10 described above is able to effect a measurement only for a carrier film carrying a blood serum which is formed of a cellulose acetate film but is unable to do so for a carrier film other than this. As a carrier for a blood serum other than the carrier 1 formed of a cellulose acetate film, an agar, starch, polyacrylic amide-gel film or the like is typical. These gel films are much thicker than the cellulose acetate film, specifically about 1 mm thick compared with 0.1 to 0.15 mm thick of the latter film and is weak in strength so that most of these films may be reinforced by placing them on a glass or a plastic plate. When the measurement is conducted using such a gel carrier reinforced by a glass plate with the conventional densitometer 10 shown in FIG. 1, it is impossible to feed the gel carrier by means of rollers 13a.sub.1, 13b.sub.1 to 13a.sub.4, 13b.sub.4 since the rigid plate does not curve therearound. Even if a plastic plate for reinforcing a gel carrier film is used by thinning it so as to easily curve around the rollers, the gel layer is disadvantageously too thick to peel from the plastic plate and may be damaged by being caught between the rollers during conveying with the rollers. To eliminate this disadvantage, the following idea occurs that the upper rollers 13a.sub.1 to 13a.sub.4 among the four pairs of rollers 13a.sub.1, 13b.sub.1 to 13a.sub.4, 13b.sub.4 and the light receiver 15 are constructed to be integral with the cover 16 in such a manner that they are integrally removable and after a gel carrier is placed on the transparent plate 21 the cover 16 in integral with rollers 13a.sub.1 to 13a.sub.4 and receiver 15 which have been removed are again placed in position to effect the density measurement of fractionated patterns. However, this requires much time and labor in the measurement. At this time, since the gel carrier need not be immersed in the clearing liquid 11, the latter must be removed from the vessel 12 or the measurement is effected in the clearing liquid 11 which is left as it is and thereafter clearing liquid adhered to the carrier must be removed. Consequently, the density measurement of fractionated patterns for proteins of a blood serum which are formed on the gel carrier requires much time so that it will be difficult to effect a rapid analysis.